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Publication numberUS2453914 A
Publication typeGrant
Publication dateNov 16, 1948
Filing dateApr 10, 1944
Priority dateApr 10, 1944
Publication numberUS 2453914 A, US 2453914A, US-A-2453914, US2453914 A, US2453914A
InventorsGeorge M Hollenback
Original AssigneeGeorge M Hollenback
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Device for mixing plaster compounds and mixtures
US 2453914 A
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Description  (OCR text may contain errors)

Nov. 16, 1948. G. M. HOLLENBACK I 2,453,914

DEVICE FOR MIXING PLASTER COMPOUNDS AND MIXTURES V 2 Sheets-Sheet 1 Filed April 10, 1944 3 -\\v\\\ y//////// ////////////////ll {mum g is mam;

Jan 4 INVEN TOR, 650. /7 #01. L EA/anc/r;

NOV. 16, 1948. HOLLENBACK 2,453,914

DEVICE FOR MIXING PLASTER COMPOUNDS AND MIXTURES Filed April 10, 1944 2 Sheets$heet 2' lllllllll INVENTOR, 650, /7 #0; Emma/(- Patented Nov. 16, 1948 STATES ATENT OFFICE George M. Hollenback, Los Angeles, Calif.

Application April 10, 1944, Serial No. 530,298

2 Claims.

The present invention relates to methods and devices for mixing plaster mixtures or compounds. The device is particularly adaptable when the plaster so mixed is to be used for the purpose of making castings or molds for the casting of metal, or other substances requiring dimensional accuracy.

The invention is particularly adaptable for use by manufacturing dentists in the making of inlays, crowns, and other articles.

The invention has for an object the provision of a device capable of forming a plaster mixture or compound which is substantially free from air, and is smooth and dense in character, with the result that when the plaster is used for molding purposes, the casting will have a smooth dense surface free from pits and other imperfections. The device is inexpensive in cost of manufacture, and capable of producing superior results for the purpose intended.

With the above mentioned and other objects in view, the invention consists in the novel and useful provision, formation, construction, association, and relative arrangement of parts, members and features, all as shown in certain embodiments in the accompanying drawings, described generally, and more particularly pointed out in the claims.

In the drawings:

Figure 1 is a perspective view of the device as an entirety,

Figure 2 is a top plan view of the device,

Figure 3 is a sectional view on the line 33 of Figure 2,

Figure 4 is a transverse sectional view on the line 4-4 of Figure 8,

Figure 5 is a plan View looking in the direction of the arrow 5 of Figure 4,

Figure 6 is a bottom plan view looking in the direction of the arrow 6 of Figure 4,

Figure '7 is a side elevation of the cover and certain associated elements of the invention,

Figure 8 is a side elevation of the mixing bowl of the invention,

Figure 9 is a plan view looking in the direction of the arrow 9 of Figure '7,

Figure 10 is a flask or ring used in the practice of the invention, and

Figure 11 is a device which is adapted to carry the pattern and used in the practice of the invention.

Referring now to the drawings, I have, in Figure 1, shown the device as an entirety and in assembled form. This device includes a mixing bowl I which may be utilized as the member with- 2 in which the desired amount of plaster and water is placed and initially mixed in any approved manner, such as by a spatula. In the present instance, the mixing bowl is shown as being formed of semi-flexible rubber, although it is evident that other materials might be utilized. The device also includes a cover or cap 2, adapted to be fitted over the top of the mixing bowl, and which cap carries a means 3 for agitating the plaster within the mixing bowl. In addition, the cap supports means 41 constituting a vibratory member for causin the mixed plaster to move from the mixing bowl during one phase, in the use of the device. Means 5 is associated with cap 2, the said means effecting communication with the interior of the mixing bowl when the cap is placed thereover, and which means is associated with some form of vacuum producing device for the purpose of exhausting air from the plaster mixture within the bowl. A flask or ring 6 cooperates with the mixing bowl I and a former member I. The ring 6 is adapted to fit against a portion of the mixing bowl to receive the plaster mixture after said mixture has been thoroughly agitated, and to flow around a pattern carried by the former member 1, the pattern being positioned within the ring or flask.

As depicted by Figures 7, 8, 10 and 11, the device as an entirety has its several component parts shown separated. The mixing bowl may assume any configuration desired. The shape shown in Figures 4 and 8 is useful when the plaster used constitutes an investment material, such as used by dentists. The mixing bowl includes a curved side wall 8 provided with a rim flange 9 and a thickened base 10. This base has a central orifice or opening H communicating with a counterbore or opening of enlarged diameter 82. The base is formed with an annular groove 13, the construction providing as between opening l2 and said groove a thin annular wall [4. As before stated, the mixing bowl is adapted to have the plaster placed therein. If the plaster constitutes an investment material, the investment material is mixed with water by means of a spatula, while in the mixing bowl. To prevent the investment material from passing through the opening II, I may plug said opening with a cork or other means. The bowl is adapted to fit against the cap 2, while the investment material is being a itated by the means 3.

The cap 2 is provided with a rim flange l5, which overlaps the flange 9 of the bowl. The inner surface of the cap is provided with an annular depending bead it which indents a soft rubber gasket I! mounted on the flange 9 of the bowl. Obviously, this aids in sealing the cap against the bowl. The cap is provided with a central bore [8, within which bore is positioned a sleeve-type bearing Hi. This bearing is held to the cap in any approved manner, and the said cap is centrally reinforced by an annular top plate 20. Passed through the bearing is a shaft 2|. The shaft is provided with an enlarged head 22 formed with a kerf 23. Interposed between an end of the bearing sleeve l9 and the portion 24 of the head and surrounding shaft 2| is a resilient sleeve 25. The shaft is provided with means 26 for maintaining the shaft within the bearing IS. The means 3 for mixing the plaster constitutes a paddle secured to the shaft at 21. This is accomplished by splitting the end of the shaft and fitting the paddle therein, as see Figure 9. This .paddle is in the form of a semi-circular disc provided with edge notches 28, 29 and 3!]. The arrangement of the paddle is such as to fit closely within the mixing bowl so the plaster is smoothed in ribbon streams during the agitation or mixing caused by rotation of the paddle.

The means 4 constitutes in its simplest embodiment some device for vibrating the cover or cap 2, As illustrative of such a means, I have provided a clamp 3i secured to the sleeve bearing IS, the clamp carrying an outwardly extending shaft 32, upon which is mounted an ofi-center weight 33. This weight is provided with a kerf 34..

Part of the means includes a part having a nipple 35 secured to the cap 2 adjacent bore [8. Suitable means 3?, such as a rubber hose, secured to nipple 36, leads to a vacuum pump or other air exhausting means, indicated diagrammatically at 3,8.

The flask B constitutes an elongated tubular member which may be provided with a beveled edge 39.

The former 7 provides a base member for the flask and centrally carries a sprue pin 40. This sprue pin is embedded in a semi-spherical part 4!. It is also to be observed that the former is provided with three step portions 42, 43 and 44 of different diameter. When the bottom of the flask engages the former I, the base rests. upon the portion 43, while portions 4! and Mfit within the flask.

The operation, uses and advantages of the invention are as follows:

We assume that the material to be mixed is for dental purposes, and constitutes investment material. This material is a fine powder adapted to be mixed with water. The mixing bowl is first plugged by placing a cork or similarmeans in opening H, and thereafter the powder is placed in said bowl and water added, the entire mass be ing initially stirred by some means, such as a spatula. As the mixed material is relatively stifi or viscous after mixing, the plug may be removed from the opening H. The bowl is then brought into pressure engagement with cap 2, which will cause the bead l6 to indent gasket ll. The flask is then moved within the confines of wall I 4 and into end engagement with a gasket 45, followed by engagement with said flask of former member I. This former member carries on the sprue pin the desired pattern. It is intended that no air leakage should occur between the sprue pin and the former member I. The bowl is then placed under vacuum conditions by connecting the same with pressure reduction apparatus 38. This pressure reduction apparatus is not detailed,

as any type of pressure reduction apparatus will do. One type that I have employed includes a connection with a spigot so that as water is passed through said spigot, a suction results in the line communicating with the nipple 38. Under pressure reduction, the former member 1 is drawn tightly against the flask 6, the flask 6 held in sealing engagement with the bowl around the opening H, and the cover 2 sealed on the bowl and the entire investment material subjected to a vacuum condition. If now the paddle or agitator 3 is rotated within the bowl, the relatively stifif investment material is intimately mixed and smoothed in ribbon streams, and any air therein, such as air bells, is removed from said material. The agitator 3 is operated by engaging a conventional power drive (not shown) with the kerf 23 of the head 22 of the shaft 2|.

While the vacuum is being maintained, I then subject the entire device to a vibration by rapidly rotating means 4. This is accomplished by disconnecting the drive from the agitator 3 and connecting it to the vibrator 4 through engagement with the kerf 34 of the weight 33 on the shaft 32. This causes the investment material to pass through the opening H and into the flask 6 surrounding the pattern, sprue pin, and part 4| of member 7. After a given length of time, usually a few seconds, the investment material is entirely moved from the bowl into the flask, whereupon the vacuum may be broken, the cover 2 removed from the bowl, and the flask 6 separated from the bottom of the bowl. The investment material is allowed to harden. Upon removal of member 1 with its sprue pin, the pattern remains in the mold, but the pattern is readily removed by heating the mold, the pattern material passing through the sprue which has previously been formed by the sprue pin.

To make a casting, it is simply necessary to melt the material, such as gold, and pour it into 1e basin portion which has been formed by part 3! of member 7, the molten metal passing through the sprue and into the mold cavity.

Actual use of the present device has demonstrated and shown that accurate castings are made, the casting being hard and dense, with a smooth surface free from pits and imperfections or small openings, such as would be otherwise present if all air had not been removed from the investment material.

In some instances, it may be desired to make a plaster mix which is substantially free from, entrapped air. To do this, I need simply to plug the opening H and thereafter rotate the paddle while maintaining a sub-atmospheric condition within the bowl.

I claim:

l. A device of the character described including a mixing bowl having a discharge opening and in which a relatively stiff plastic mix is placed, a cover to seal said bowl, a rotatable paddle in the bowl conforming to the interior of the same, means to smooth the mix in ribbon streams during agitation caused by rotation of the paddle, means to maintain the sealed bowl under subatmospheric pressure, a flask in sealing engagement with the bowl and aligned with the discharge opening, and separate means to vibrate the bowl to discharge the mixed material therefrom into the flask while the bowl is still under sub-atmospheric pressure.

2. A device of the character described including a. mixing bowlin which a relatively stiff plastic flask while the same is still sealed to the bowl by sub-atmospheric pressure.


REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,741,646 Nielsen Dec. 31, 1929 1,751,097 Nelson et a1. Mar. 18, 1930 1,839,082 Burgard Dec. 29, 1931 2,165,466 Erdle July 11, 1939 2,183,763 Brown Dec. 19, 1939 2,192,902 Erdle Mar. 12, 1940 2,295,136 Stiers Sept, 8, 1942 2,344,754 Vang Mar. 21, 1944

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1741646 *Jun 22, 1926Dec 31, 1929Claudius NielsenMixing machine
US1751097 *Sep 19, 1928Mar 18, 1930Nelson Earl AllenDental investment mixer
US1839082 *Jun 26, 1926Dec 29, 1931Louis C BurgardMixer
US2165466 *Dec 28, 1936Jul 11, 1939Dental Res CorpMethod of making shell-like porcelain tooth structures
US2183763 *Sep 23, 1938Dec 19, 1939Davis BrownSlip deaerator
US2192902 *Jan 20, 1936Mar 12, 1940Dental Res CorpMethod of molding dentures
US2295136 *Feb 13, 1940Sep 8, 1942Stiers Carl JMixer
US2344754 *Aug 29, 1942Mar 21, 1944Stevenson Jordan & Harrison InDrying of vegetables
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2696022 *Apr 23, 1951Dec 7, 1954SteinbockInvestment mixer
US2711306 *Nov 23, 1953Jun 21, 1955Levi LeoneMagnetic stirrer
US2777177 *Nov 9, 1951Jan 15, 1957Edmund A SteinbockInvestment mixer
US2884963 *Apr 27, 1956May 5, 1959Prec Metalsmiths IncInvesting apparatus
US3131912 *Feb 1, 1954May 5, 1964Edmund A SteinbockInvestment mixer
US3195866 *Jan 22, 1962Jul 20, 1965Coats John NStock consistency blending apparatus
US3243163 *Jul 1, 1963Mar 29, 1966Norton American Aviat IncViscous and non-viscous material processing system
US3358971 *Jun 21, 1965Dec 19, 1967Whip Mix CorpInvestment mixer
US3366369 *Oct 7, 1966Jan 30, 1968Giacinto Guido FinaDevice for mixing and transferring under vacuum special pastes and gypsum for use in dental and jeweller's art
US3559961 *Aug 16, 1968Feb 2, 1971Gunnar BergendalApparatus and method for the production of dental mixtures poor in porosity
US4197646 *Dec 5, 1977Apr 15, 1980Morrison Paul MHousing for dental amalgamator
US4653568 *Mar 17, 1983Mar 31, 1987Fabraze, Inc.Foundry process and apparatus, including mixing investment composition under vacuum
US4973168 *Jan 13, 1989Nov 27, 1990Chan Kwan HoVacuum mixing/bone cement cartridge and kit
US5121990 *Dec 19, 1986Jun 16, 1992Jacques GuietDevice for the preparation of a paste
US5328262 *Feb 3, 1993Jul 12, 1994Mit AbMethod for producing reduced porosity bone cement
US5348391 *Nov 16, 1993Sep 20, 1994Murray William MManual bone cement mixing method
US5368386 *Nov 16, 1993Nov 29, 1994Murray; William M.Manual bone cement mixing device
US5395167 *Nov 16, 1993Mar 7, 1995Murray; William M.Manual bone cement mixing system
US5409311 *May 17, 1993Apr 25, 1995Vosschemie GmbhDevice for the production of medium-viscous or more highly viscous dual-component of multi-component compounds by intermixing the components
US5472445 *Sep 20, 1993Dec 5, 1995Zimmer, Inc.Device for minimizing porosity in bone cement utilizing centrifugation and vacuum
US5501520 *Apr 26, 1994Mar 26, 1996Mit AbDevice for producing reduced porosity bone cement
US5645347 *Nov 17, 1993Jul 8, 1997Draenert; KlausMixing apparatus with mixing rod supporting lid
US5797680 *Sep 5, 1996Aug 25, 1998Murray; William M.Manual bone cement mixing system with vacuum pump start-stop device
US6120174 *Jan 14, 1999Sep 19, 2000Bristol-Myers SquibbApparatus and method for mixing and dispensing bone cement
US6789934 *May 2, 2002Sep 14, 2004Don Evan GoddardVacuum mold making and casting equipment
US6945688 *Jan 10, 2002Sep 20, 2005Stryker InstrumentsContainer assembly for mixing materials
US6994465Mar 13, 2003Feb 7, 2006Stryker InstrumentsMixing assembly for mixing bone cement
US7160020 *Apr 24, 2006Jan 9, 2007Kyphon Inc.Methods for mixing and transferring flowable materials
US7278778Jan 9, 2007Oct 9, 2007Kyphon Inc.System for mixing and transferring flowable materials
US7645066Dec 12, 2005Jan 12, 2010Stryker CorporationMethod of mixing bone cement with two mixing paddles
US7967499Jan 12, 2010Jun 28, 2011Stryker CorporationBone cement mixer with two paddles, the paddles arranged to limit longitudinal movement
USRE35276 *Nov 23, 1992Jun 18, 1996Chan; Kwan-HoVacuum mixing/bone cement cartridge and kit
U.S. Classification366/77, 366/139
International ClassificationB01F7/16, B01F13/00
Cooperative ClassificationB01F7/1695, B01F13/002, B01F2215/0029
European ClassificationB01F7/16S